1. Field of the Invention
This invention relates to a process for treating fish bodies. More particularly it relates to a process for treating fish bodies which comprises treating, for example, fish bodies with a protease and separating at least one product selected from among fish bones, fish oil and partially decomposed fish protein from the obtained mixture.
2. Description of the Prior Art
A conventional process for producing fish meal and fish oil from fish bodies and remnants obtained after processing the same comprises: pre-treating, e.g., cutting, crushing or grinding a raw material if required; steaming the same; pressing the same to thereby separate liquid matters including fish oil; drying the residual solid matters; grinding the dried matters to give fish meal, if required; separating the fish oil from the liquid matters; and concentrating the residual liquid matters to give fish soluble. Since this process involves no step for removing fish bones, the fish meal thus obtained contains a large amount of fish bone pieces, which makes it difficult to use the same as a component for highly proteinous feeds or highly proteinous food materials. Further the above-mentioned process involves thermal treatment step(s) such as steaming, which brings about thermally denatured proteins. Thus the obtained products are not always satisfactory as proteinous feeds or proteinous food materials in some cases.
A so-called extract, which serves as the raw material for a seasoning, is produced by completely liquefying fishes or shellfishes through autolysis and/or decomposition with a protease in the presence of several times as much water for a long time. In this process wherein fish bodies are used as the starting material, fish bones contained therein can be readily separated. However it is impossible to obtain fish proteins in the form similar to that of fish meat thereby, since the fish meat is liquefied through the decomposition.